The rover already did a little test-drilling Tuesday on the target rock known as “Windjana,” named for a gorge in Western Australia, according to officials at Jet Propulsion Laboratory in La Canada Flintridge, which manages the Mars robot. The operation left a hole in the fine-grained sandstone that was about 0.8 inches deep with a heap of powdery pulverized rock surrounding it. The dug-up rock powder was a grayish color, in stark contrast to the reddish brown of the surface, scientists said.

"The team intends to have Curiosity drill for a powdered-rock sample at this site in the coming days," JPL spokesman Guy Webster said.

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Windjana is intriguing to researchers in part because “some portions of the rock are harder than others, creating the interesting bumpy textures," Caltech scientist and Curiosity team member Melissa Rice said in a statement.

Scientists want to understand why some sandstones are harder than others because over long timescales, the softness or hardness of a rock has a role in shaping the landscape. That’s because softer rock can erode away more quickly while harder rock remains intact for much longer.

Studying these rocks will also give them clues about what the environment was like at the time, scientists said.

"We want to learn more about the wet process that turned sand deposits into sandstone here," Curiosity’s lead scientist, Caltech geologist John Grotzinger, said in a statement. "What was the composition of the fluids that bound the grains together?"

Curiosity’s first two drilling targets were two rocks that sat near each other in a place called Yellowknife Bay, about 2.5 miles northeast from its current location. Last year, the drilled mudstone rocks revealed a past watery environment rich in chemical elements necessary for life as well as a chemical energy source that could have fueled Earth-like organisms like chemolithoautotrophs.

Curiosity’s ultimate goal is Mt. Sharp, the three-mile high mound in the middle of Gale Crater whose layers of sedimentary rock could potentially reveal a range of past habitable environments on Mars.